Abstract: Cryomodules are the smallest units of a superconducting linear accelerator. The thermodynamic property of cryomodule at low temperature can influence the operating cost and efficiency of cryogenic system. Cryomodule heat load include the static heat load and the dynamic heat load. The thermal shield, cavity, tuner, coupler and insulation support have been studied. The key factors that can influence the heat load also have been analyzed. The results show that the heat load of cryomodule can meet the design requirements and can set the foundation of superconducting linear accelerator.